1. Field of the Invention
The present invention relates to a system designed such that, in the event that some program data, map data or the like fails and becomes impossible to use, the system executes data recovery by requesting a remote information center to send that data. The present invention also relates to such equipment for motor vehicle use, and a medium for recording a data recovery program.
2. Description of the Related Art
In Japanese Patent Laid-open Application No. Hei 3-270446, a technique was disclosed in which, if some portion of the data stored in a facsimile machine should fail, the facsimile machine would detect the data failure and request a remote backup center, which previously backed up all data including system data and telephone numbers stored in that facsimile machine, to send the original data to replace the failed data.
In this previous technique, however, because the facsimile machine was designed to issue a request for data transmission to the remote center immediately upon the occurrence of data failure, regardless of whether or not the facsimile machine requires the failed data promptly, such a problem arose that its normal communication function had to be disabled during the period from data transmission request until data recovery.
Therefore, if, for example, the above-mentioned technique is applied to a navigation system installed on a motor vehicle, and whenever any portion of the map data used in the navigation system has failed and has been put into the unusable state, the request for map data transmission is issued to the information center, even if there is no prompt need of that portion of the map data (for instance, the requested map data relates to an area that is a long way off from the current position of the motor vehicle). Such data recovery work for the data of less importance increases the idle load on a navigation controller and related devices and there is a possibility of affecting the inherent navigation function of the controller.